Automatic child-resistant sliding door lock

ABSTRACT

A magnetically actuated safety lock device provides automatic locking capability to doors such as sliding glass patio doors and prevents unsupervised opening of the door by young children, thereby barring their access to dangerous environments. When the sliding door is closed, it is automatically locked. The lock device is installed in a position high upon the sliding door to prevent actuation by young children and requires no permanent modification to the door on which it is installed. The lock device consists of a locking assembly and a magnetic key. The locking assembly includes a magnetized latch assembly and a mounting bracket. The latch is held in the locked position by gravity and is only rotated into the unlocked position through the application of hand pressure or the repulsive force of the magnetic key. The doors can be unlocked from both inside and outside the door. Upon removal of either the magnetic force or hand pressure, the latch rotates back into the locked position. The latch is designed with an angled surface on one side such that as the user closes the door behind him, the door can close normally. This angled surface in the latch allows the door to slide along its track in the closing direction and, as the door edge touches the latch at the angled surface, the latch is rotated by the door into the unlocked position. Once the frame of the door slides completely past the latch, the latch rotates back into the locked position.

BACKGROUND OF THE INVENTION

This invention relates to child-resistant door locks. More particularly,it refers to a magnetically controlled means for opening automatic doorlocking mechanisms.

A variety of locking mechanisms exist for use in conjunction withsliding doors such as glass patio doors. These devices include bars,pins, track-mounted stops and latch-keeper devices. The bar-type lockingmechanism prevents the door from sliding by spanning the distancebetween the edge of the door and the door jamb, thereby reacting to adoor opening force in compression. Pins prevent the door from sliding bypinning the door to a stationary member such as the door frame of theopposite door, thereby reacting to a door opening force in shear.Track-mounted stops are secured to the track on which the sliding doorglides and block the door from sliding along the track once the doorengages the stop. Finally, latch-keeper combinations consist of a latchin the door frame and a keeper in the door jamb which engage together tosecure the door frame to the door jamb.

In the case of bar-type, pin-type and track-mounted stop configurations,it is not possible to lock or unlock the door from the face of the dooropposite the face on which the pin-type, bar-type or track-mounted stopis installed. In the case of latch-keeper mechanisms, the locking andunlocking means is normally found at an elevation accessible to smallchildren and these mechanisms are not normally constructed to preventunlocking from the interior of the building in which the door isinstalled. In more sophisticated versions of these types of mechanisms,key actuated latch-keeper lock mechanisms may be employed. This type oflock mechanism is expensive, is difficult to add to pre-existing doorinstallations, and requires permanent modifications to the door.Pin-type and bar-type locking devices also require permanent doormodifications to doors on which they are installed.

The present invention is intended to overcome the deficiencies of theprior art. The door lock of this invention can be easily installed bythe door owner without the use of tools and requires no permanentmodification to the door on which it is installed. The door lock of thisinvention may be removed easily from the door when there is no more needfor it. On the side of the door on which the inventive locking device isinstalled, it can be opened by anyone able to reach to the elevation ofthe device as installed. On the opposite face of the door, typicallyoutside the building in which the door is installed, the user grasps amagnetic key stored at a high elevation near that door face and placesthe key against the outer surface of the door, thereby causing the latchto rotate into the unlocked position as will be described in greaterdetail hereinafter.

The following prior art is known to Applicant:

U.S. Pat. No. 4,848,812 to Slaughter discloses a concealed safety lockhaving a bolt in the form of a cylindrical magnet that may be movedthrough the use of a magnetic key.

U.S. Pat. Nos. 4,919,464 and 5,076,623, both to Richards, disclose latchmechanisms for use, for example, in holding a door leaf closed andinclude a pivotable assembly carrying a magnet that holds a magneticallyattractive material attached to the door leaf closely adjacent theretoin one position thereof, and is pivoted away from that positionresponsive to close proximity of a magnetic key, thereby allowing thedoor leaf to be opened.

U.S. Pat. No. 5,188,405 to Maccaferri discloses a locking device for alatch similar to that of the Richards patents but including the furtherprovision of a locking mechanism designed to hold the latch in an openposition.

U.S. Pat. No. 5,485,733 to Hoffman discloses a concealed magnetic lockfor cabinet closure that includes a pivotable magnetic piece biased inone direction through a built-in magnet and pivotable away from thatposition through the use of a magnetic key.

The present invention differs from the teachings of these patents ascontemplating a latch designed to move and lock through the force ofgravity to a latched position automatically and may be moved to anunlatched position through the repelling force between a latch-mountedmagnet and a magnet mounted in a key.

SUMMARY OF THE INVENTION

The present invention relates to an automatic child-resistant slidingdoor lock. The present invention includes the following interrelatedobjects, aspects and features:

(1) In a first aspect, the present invention is intended to be easilyinstalled by the door owner on an existing sliding door such as a set ofglass patio doors. The inventive lock is intended to be mounted on thedoor through the use of adhesive and may be removed subsequently whenappropriate, without causing any cosmetic damage to the door.

(2) The inventive lock includes a latch pivotably mounted on a bracketwith the pivot point and latch geometry being so chosen that the latchtends to rotate in one desired direction of rotation. An angled lowersurface is provided in which a magnet is embedded with this angledsurface pressing flat against a portion of the bracket immediatelyadjacent to and parallel with the door surface in the latched positionthereof.

(3) In the latched position of the latch, an upper corner thereofextends outwardly to a position interfering with sliding movements ofthe door, thereby preventing such movements.

(4) Adjacent the upper surface, an upper angled surface is provided foran important purpose. When the latch has been moved to a positionallowing the door to slide toward the open position, after the latchpasses the frame of the fixed piece of glass forming the other half of aglass patio door system, the user's fingers may no longer engage thelatch and, through force of gravity, it pivots to the normally latchedposition. Without the upper angled surface, when one would subsequentlymove the door toward the closed position, the latch would be captured ona side of the frame of the fixed piece of glass remote from the locationcorresponding to complete closure of the sliding glass door. When theangled surface engages the frame of the fixed piece of glass, furthermovement causes the latch to pivot to a position allowing it to slidepast that frame to the closed position of the door, and when the latchclears that frame, it automatically pivots to an interfering positionwith respect to that frame, thereby preventing renewed opening of thedoor without pivoting of the latch.

(5) A key is provided that permits opening of the latch from a locationoutside the building where the latch is mounted. The key includes agripping portion and a permanent magnet embedded therein with its polesarranged so that the key provides a repelling force with respect to theorientation of the permanent magnet embedded in the lower angled surfaceof the latch. In this way, when the key is engaged on the door surface,for example, the glass surface adjacent where the latch is mounted, therepelling force of the magnet embedded therein repels the magnet on thelower angled surface of the latch, thereby causing the latch to pivot toa position wherein the upper corner thereof no longer interferes withsliding movements of the door, whereby, the door can be re-opened.

(6) Once the door has been slid open, the key may be removed fromadjacent the latch and may be restored to its storage location,preferably, a "key-keeper" mounted on an outside wall of the building atan elevation high enough so that it may not be reached by smallchildren.

As such, it is a first object of the present invention to provide anautomatic child-proof sliding door lock.

It is a further object of the present invention to provide such a doorlock that automatically pivots through the force of gravity to a latchedposition and that may be pivoted from that latched position throughapplication of the repelling force of a magnetic key.

It is a yet further object of the present invention to provide such adoor lock including an upper angled surface situated to prevent thelatch thereof from being captured on the other side of an adjacent frameof a fixed portion of the building structure when the door is being slidtoward a closed position.

These and other objects, aspects and features of the present inventionwill be better understood from the following detailed description of thepreferred embodiment when read in conjunction with the appended drawingfigures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a sliding glass door having theinventive lock installed thereon.

FIG. 2 shows a front perspective view of the latch of the inventive doorlock.

FIG. 3 shows a rear perspective view of the latch of the inventive doorlock, inverted with respect to the orientation of FIG. 2, to showdetails of the embedded magnet.

FIG. 4 shows a perspective view of the inventive door lock in the lockedposition viewed from an opposite end of the latch as shown in FIG. 1.

FIG. 5 shows an opposite end perspective view of the lock assembly tothat of FIG. 4, but with the latch in the unlocked position.

FIG. 6 shows a top view of the door lock in the locked position with theassociated door shown partially in cross-section.

FIG. 7 shows a side sectional view along line 7--7 of FIG. 6 with thelatch in the locked position.

FIG. 8 shows a top view of the door lock in the unlocked position andwith the associated door shown partially in cross-section.

FIG. 9 shows a sectional view along line 9--9 of FIG. 8, with the latchin the unlocked position and with the associated door shown partially incross-section.

FIG. 10 shows a view similar to that of FIG. 7 but with shims beingprovided on the mounting bracket to cause a larger portion of the latchto protrude outwardly in the locked position thereof.

SPECIFIC DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference, first, to FIGS. 1 and 6, a typical door on which theinventive door lock may be applied is generally designated by thereference numeral 1 and is seen to include a first frame 2 and a secondframe 3, with the first frame 2 enclosing a piece of glass 4 and withthe second frame 3 enclosing a piece of glass 5. The frame 2 and thepiece of glass 4, together, comprise a sliding glass door 12 guided by atrack (not shown) in sliding movements with respect to the frame 3.Piece of glass 5 is included in sliding glass door 18. Door 18 remainsstationary with respect to door 12. The double-headed arrow 6 depictsthe directions of sliding of the sliding glass door 12. Viewing of FIGS.6 and 8, the side 7 of the piece of glass 4 is inside the building (notshown) in which the door assembly 1 is mounted while the side 8 of thepiece of glass 4 is outside that building.

With reference to the figures, the present invention is generallydesignated by the reference numeral 10 and includes a bracket 11 as wellas a pivotably mounted latch 30. With reference, in particular, to FIGS.7 and 9, the bracket 11 includes a thin, rear wall 13 affixed to thesurface 7 of the piece of glass 4 by a suitable adhesive layer 15.

With particular reference to FIGS. 4 and 5, the bracket 11 has a portionof generally inverted U-shaped configuration including a horizontalportion 17 and vertically depending legs 19 and 21. The legs 19 and 21have respective holes 23 and 25 therethrough that are axially alignedwith one another and are provided for a purpose to be described ingreater detail hereinafter.

With reference to FIGS. 2 and 3, the latch 30 includes side walls 31 and33. With reference to FIG. 2, an upper edge 35 and an upper angledsurface 37 are provided for a purpose to be described in greater detailhereinafter.

As seen in FIGS. 3, 7, and 9, the latch 30 also includes a lower angledsurface 39 on a lower half thereof in which is embedded a permanentmagnet 41 having its poles arranged in the orientation shown in FIGS. 7and 9. The latch 30 also includes an upper angled surface 38 on theupper half thereof. The lower angled surface 37 and the upper angledsurface 38 are provided for a purpose to be described in greater detailhereafter.

With reference to FIGS. 2 and 3, a pin 43 extends outwardlyperpendicular to the sidewall surface 31 while a pin 45 extendsoutwardly perpendicularly to the sidewall surface 33 with the pins 43and 45 being axially aligned with one another. The surface 37 extendsobliquely with respect to the axis of alignment of the pins. As shouldbe understood from comparing FIGS. 2 and 3 and FIGS. 4 and 5, the pin 43is received within the opening 23 of the bracket 11 while the pin 45 isreceived within the opening 25 of the bracket 11. The dimensions of thepins 43 and 45 is such that the latch 30 freely pivots within theopening 20 defined between the legs 19 and 21 and the horizontal portion17.

With reference to FIG. 7, the pins 43 and 45 (not shown in this view)are so located on the latch 30 that the weight distribution thereof,also taking into account the location of the magnet 41, causes the latch30 to tend to freely pivot to the orientation shown in FIG. 7 with lowerangled surface 39 thereof engaging the lower surface 14 of the thin,rear wall 13 of the bracket 11 that acts as a limit stop limiting therotation in the clockwise direction in the view of FIG. 7 to theposition shown. In that position, the corner 47 of the latch 30protrudes into a space aligned with the frame 3 such that movement ofthe door 12 or the opposite door 18 in the opening direction thereof isprevented by engagement of the corner 47 and the adjacent structure ofthe latch 30 with the frame 3.

As should clearly be understood from FIG. 9, the latch 30 may be movedto a different position (shown in FIG. 9) wherein the corner 47 thereofno longer protrudes into a space aligned with the frame 3. In theposition shown in FIG. 9, the sliding door 12 or the opposite door 18may freely slide to the open position of the door assembly 10. Toprevent over rotation of the latch 30, the upper angled surface 38engages the upper surface 16 of the thin rear wall 13 of the bracket 11.

As best understood from FIG. 6 and 8, one may manually pivot the latch30 to the position shown in FIG. 9 whereupon the door 12 may be movedlinearly on its track (not shown) in the left-hand direction in the viewof FIG. 6 and 8, to an open position. During the opening process, thelatch 30 will move to the left of the frame 3. Once the latch 30 iscompletely to the left of the frame 3, through force of gravity, thelatch 30 will naturally swing back to the position shown in FIG. 7whereupon the corner 47 protrudes into the space aligned with the frame3 but, in this case, closer to the glass 5. Thus, from that position,when it is desired to move the frame 2 in the opposite direction toclose the door 1, without the upper angled surface 37, the latch 30would engage the inside surface 9 (FIG. 6) of the frame 3, therebypreventing complete closure of the sliding door portion 12. However, inlight of the inclusion of the upper angled surface 37, when the latch 30engages the frame 3, in fact, the surface 37 thereof engages the corner50 of the frame 3 with further movement pivoting the latch 30 from theorientation shown in FIG. 9 to the orientation shown in FIG. 7 to allowthe latch 30 to move past the frame 3 whereupon, through force ofgravity, its orientation is restored to the position shown in FIG. 7.

When the user is outside the building (not shown), in which the doorassembly 1 is mounted, and the latch assembly 10 is in the lockedconfiguration shown in FIG. 7, thereby precluding opening of the doorassembly 1, the present invention also includes a key 60 that may beemployed to open the latch assembly 10.

In this regard, reference is made to FIGS. 7 and 9 that show a key 60including a body 61 with surfaces 63 and 65, facilitating gripping ofthe key 60 with the fingers of the user. The key includes a forwardsurface 67 in which is embedded a permanent magnet 69 having polesoriented in a manner such that with the latch 30 in the orientationdepicted in FIG. 7, the magnetic force of like poles between the magnets41 and 69 will repel one another when the key 60 is placed in theposition shown in FIG. 9, thereby causing the latch 30 to move to theposition shown in FIG. 9, whereupon the door 12 may be slid to the openposition. When the key 60 is removed from the surface 8 of the piece ofglass 4, its magnet 69 is no longer close enough to the magnet 41 of thelatch 30 to have any effect thereon, therefore, the latch 30 movesthrough force of gravity to the orientation shown in FIG. 7.

As shown in FIGS. 7 and 9, a key-keeper 70 consists of a flat, steelplate 71 affixed to the frame 2 by a strip of adhesive 73. Of course,steel is a magnetically attractive material and the key 60 will adhereto the steel plate 71 in the manner depicted in FIGS. 7 and 9. The keycould be alternatively mounted permanently as a momentary switch overthe magnet 41 on the opposite side of the glass.

With reference to FIG. 10, a slight modification is shown wherein a shim75 is interposed between the thin, rear wall 13 of the bracket 10 andthe surface 7 of the piece of glass 4. As shown in FIG. 9, the adhesive15 is employed to adhere the thin, rear wall 13 to the shim 75 and theshim 75 is adhered to the surface 7 of the piece of glass 4 by anotheradhesive layer 77. Any number of shims such as that which is depicted bythe reference numeral 75 may be employed to appropriately adjust theposition of the latch 30 with respect to the piece of glass 4 and theframe 3 so that in the position of the latch 30, best seen in FIG. 7,the corner 47 thereof protrudes sufficiently in the way of an areaaligned with the frame 3 so that the latch 30 is operative.

In the preferred embodiment of the present invention, the pins 43 and 45are made of a suitable non-corroding material having sufficient strengthand stiffness to fully withstand loads that might be encountered when auser attempts to open the door assembly 1 without unlocking the lockingdevice 10. In the preferred embodiment, the material of the pins 43 and45 is stainless steel.

In the preferred embodiment, the latch 30 and shim 75 as well as themounting bracket 11 are made of a high-impact strength andhigh-stiffness ABS plastic material that is ultraviolet-stable andcapable of withstanding loads that might be encountered when a userattempts to open the door assembly 1 without unlocking the lock assembly10. The bracket 11 is preferably made of a high-impact strength andhigh-stiffness thermoplastic that is ultraviolet-stable and opaque toprovide high visibility.

In the preferred embodiment, the magnets 41 and 69 are made of a ceramicmagnet material. The body of the key 60 is preferably made of a similarmaterial to that of the bracket 11.

As such, an invention has been disclosed in terms of a preferredembodiment thereof which fulfills each and every one of the objects ofthe invention as set forth hereinabove and provides a new and usefulautomatic child-proof sliding door lock of great novelty and utility.

Of course, various changes, modifications and alterations in theteachings of the present invention may be contemplated by those skilledin the art without departing from the intended spirit and scope thereof.

As such, it is intended that the present invention only be limited bythe terms of the appended claims.

I claim:
 1. In a sliding door assembly moving along a horizontal planeincluding a sliding door having a frame adjacent a flat surface, saidsliding door being slidable past a closely adjacent vertical wall of anassociated structure, the improvement comprising a lock assemblyincluding:a) a bracket mountable on said flat surface; b) a latchpivotably mounted on said bracket about a pivot axis and including alower half with a lower surface limiting a degree of pivoting of saidlower half toward said flat surface, said latch pivot axis being locatedsuch that said latch is weight-biased, by force of gravity, to pivot ina direction toward engaging said lower surface with said flat surfaceand to rest normally in a locked position; c) said latch including anupper corner protruding adjacent said vertical wall when said lowersurface is adjacent said flat surface, whereby said corner may engagesaid vertical wall to prevent sliding movement of said sliding door, andwherein said latch further includes a permanent magent having a surfacecomprising at least a part of said lower surface.
 2. The improvement ofclaim 1, wherein said latch has an upper angled surface extending fromsaid corner obliquely with respect to said pivot axis, said corner beingbetween said vertical wall and said upper angled surface when saidsliding door is in a closed position.
 3. The improvement of claim 1,wherein said bracket is attached to said flat surface by adhesive. 4.The improvement of claim 3, wherein said flat surface comprises asurface of a piece of glass.
 5. The improvement of claim 4, wherein saidvertical wall comprises a further frame surrounding a further piece ofglass.
 6. The improvement of claim 1, further including a key includinga further permanent magnet, poles of said magnets being so arranged thatmoving said key adjacent said latch causes said latch to pivot saidlower surface away from said flat surface.
 7. The improvement of claim6, whereby said upper corner of said latch does not protrude adjacentsaid vertical wall when said lower surface is pivoted away from saidflat surface.
 8. The improvement of claim 7, wherein said flat surfacecomprises a surface of a piece of glass.
 9. The improvement of claim 6,wherein said key includes a key-keeper comprising a flat plate made ofmagnetically attractive material and mounted adjacent said doorassembly.
 10. In a sliding door assembly moving along a horizontal planeincluding a sliding door having a frame surrounding a piece of glasshaving a flat surface, said sliding door being slidable past a closelyadjacent fixed frame having a further piece of glass therein, theimprovement comprising a lock assembly including:a) a bracket mountableon said flat surface with adhesive; b) a latch pivotably mounted on saidbracket about a pivot axis and including a lower half with a lowersurface limiting a degree of pivoting of said lower half toward saidflat surface, said latch having a permanent magnet having a surfacecomprising at least a part of said lower surface, said latch pivot axisbeing located such that said latch is weight-biased, by force ofgravity, to pivot in a direction toward engaging said lower surface withsaid flat surface and to rest normally in a locked position; c) saidlatch including an upper corner protruding adjacent said fixed framewhen said lower surface is adjacent said flat surface, whereby saidcorner may engage said fixed frame to prevent sliding movement of saidsliding door; and d) said latch having an upper angled surface extendingfrom said corner obliquely with respect to said pivot axis, said cornerbeing between said fixed frame and said upper angled surface when saidsliding door is in a closed position.
 11. The improvement of claim 10,further including a key including a further permanent magnet, poles ofsaid magnets being so arranged that moving said key adjacent said latchcauses said latch to pivot said lower surface away from said flatsurface.
 12. The improvement of claim 10, whereby said upper corner ofsaid latch does not protrude adjacent said fixed frame when said lowersurface is pivoted away from said flat surface.
 13. The improvement ofclaim 11, wherein said key includes a key-keeper comprising a flat platemade of magnetically attractive material and mounted adjacent said doorassembly.